This essay takes as its starting point the recent phenomenon of constructed documentaries, which require participants to act as if in a historical time or place that is not their own. Noting that there is little critical consensus about, though much interest in, what kind of acting is undertaken, the essay explores some of the problems and issues that arise, drawing on an essay written by the actor/director Michael Kirby (From Acting to Non-Acting). Kirby's methodology is applied to two BBC Cymru Wales constructed documentaries, Coal House (2007) and Coal House at War (2008). It is argued that acting in such programmes is not a fixed state; rather, participants move along an acting/non-acting continuum, which frequently requires them to hold two time frames of their real, contemporary world and their reconstructed world in tension. The analysis is informed by research with audiences of both series.